Topic: Future changes and uncertainties of rainfall in California, USA

Speaker: Professor Dong Lu

Center for Frontier Science in the Abyssal Sphere and Earth System, Ocean University of China | Key Laboratory of Physical Oceanography, Ministry of Education

Time: 10:00-11:30, January 6, 2022 (Thursday)

Tencent Meeting: 293 905 390

Introduction to the Lecture:

California, located in the transitional zone between subtropical arid climate zone and mid-latitude storm axis climate zone, has a typical Mediterranean climate, with the main climate features being warm and humid winter and hot and dry summer. Against the backdrops of global warming, the study predicts that the wet season in California will become stronger and shorter in the future due to the increase of water vapor caused by warming and the seasonal difference of uneven distribution of land and sea. Further studies have found that the uniform warming of the global SST is the main cause of California's wetting in winter, while there are great differences in the east-west gradients of SST in the tropical Pacific Ocean, which bring great uncertainty to the future forecast of rainfall in California. Focusing on the uncertainty of forecasting the future rainfall in California, the study has found that the deviation of the tropical rainfall double ITCZ prevalent in the current climate model can be used as an emergent constraint for forecasting the future rainfall in California, that is, the greater the deviation of the double ITCZ, the more the winter rainfall in California will be predicted, and vice versa. Besides the model deviation, the internal variability also exerts a very important impact on the decadal scale and the uncertainty of future changes of rainfall in California. Especially, the Interdecadal Pacific Oscillation (IPO) influences the westerly jet and Aleutian low pressure systems in the North Pacific Ocean, which brings great differences between the modes of rainfall in California, and its phase changes dominate the drought trend in California in the recent decades. This work is of great significance to understanding and reducing the uncertainty of future rainfall changes in California.

Profile of the Speaker:

Dong Lu, Ph.D., is mainly engaged in research on tropical air-sea interaction and climate change, and the climatic dynamic mechanism of local extreme weather. Her main academic contributions are as follows: (1) Quantify the contribution and mechanism of external forcing and internal variability to SST changes in tropical Indian Ocean and Pacific Ocean; (2) Establish the relationship between large-scale ocean and atmospheric changes and extreme weather events on the west coast of the United States; (3) Systematically assess the sources of uncertainty of future precipitation change in California and its relationship with El Nino warming SST pattern, and reveal the role of internal variability of climate system. By far, she has published 27 academic papers, of which 19 are SCI-indexed, including 1 paper published in Nature Communications. Many of her papers have been introduced and cited by high-impact journals such as Nature, Science and their series journals. She has been selected as a first level talent of the "Young Talents Program" of the Ocean University of China, and won the Young Scholar Award of Chinese-American Oceanic and Atmospheric Association (COAA) in 2017.